Treatment of motor fuel



June 8, 1937. c. D. LOWRY, JR.. ET AL 9 TREATMENT OF MOTOR FUEL FiledAug. a, 1936 @ndezzser fondeizser J92 JIZ fans.- Cizar'les D Zozu'zzy,(/zarles G. $73967".

0 constituents, such as di and tri-olefins.

. the motor fuel.

Patented June 8, 1937 PATENT OFFICE TREATMENT OF MOTOR FUEL Charles D.Lowry, Jr., and Charles G. Dryer,

Chicago, 111., assignors to Universal Oil Products Company, Chicago,I11., a corporation of Delaware Application August 8,1936, Serial No.94,988

12 Claims.

This invention relates to an improved method of producing inhibitors foruse in preventing the deterioration of cracked distillates of gasolineboiling range. More particularly, it refers to a process fordealkylating tars, with the resultant production of an inhibitor havingimproved propertles over the tar originally treated.

Cracked gasolines which are now produced in huge quantities almostinvariably contain highly unsaturated olefinic hydrocarbons whicharecharacterized by a tendency to deposit gummy resinous material uponstanding, particularly under the influence of light and air. Severalwell-known treating methods have been used for the elimination of thesegum forming constituents. Cracked distillates have been treated withsulphuric acid for the removal of the unsaturated hydrocarbons. Claytreating means have also been utilized for the elimination of theolefinic These methods, while useful, have certain inherentdisadvantages:

(1) They are quite expensive, and

(2) In addition to removing the undesirable, highly unsaturatedconstituents, they remove relatively stable olefinic hydrocarbons whichare useful and highly desirable in the gasoline.

By removing these more stable olefinic hydrocarbons the antiknock valueof the cracked gasoline is depreciated and also good gasolineconstituents'are converted to heavy polymers having no value as motorfuel. The present invention is directed to improving the value ofcertain primary tars for inhibiting the formation of these undesirablegums and the reduction in knock rating of Although it is to beparticularly pointed out that gum and color formation and reduction inantiknock value are not necessarily related, the accomplishment of thetwo objects may be brought about simultaneously.

Compounds having inhibiting effectiveness have been found in distillatesor tars. resulting from the destructive distillation of coal, ligniteand Wood. The present invention contemplates improving the inhibitingeffectiveness of these tar fractions. We have found that by treating tardistillates with hydrogen halides, comprising hydrogen chloride,hydrogen bromide and hydrogen iodide, the resultant product is aninhibitor with increased potency. The following reaction probablytypifies those which take place when treating the tar distillates with ahydrogen halide (R'OR-i-HXdROH-i-RX) R'OR represents the member ofagroup of ether-like compounds in a tar wherein R is an aryl radical,while R designates an aliphatic alkyl group of low molecular weight,usually a methyl or ethyl radical. Products of reactions of the abovecharacter are more highly phenolic and are more effective as inhibitorsthan their corresponding ethers. Alkyl halides RX are also produced.

One of the features of our invention is the regeneration of halogen acidfrom the alkyl halide. We have found that burning the alkyl halide inthe presence of air produces hydrogen halide, carbon dioxide and water.The hydrogen halide'thus liberated may be utilized again in treating thetar distillates for the production of improved inhibitors. i

The following reaction typifies those which. take place in the oxidationof the alkyl halides:

[oninr+ao-innr+'ool+mo Methyl bromide In one specific embodiment, thepresent invention comprises the treatment of tar fractions with hydrogenhalides, removing and fractionating the tar reaction products,liberating alkyl halide from the reacted mixture, oxidizing the alkylhalide produced therefrom and returning the hydrogen halide produced bythe oxidation for further treatment of the tar fractions.

The process of this invention may be carried out in a number of ways andwith various arrangements of apparatus. To illustrate the process of theinvention, one form of the apparatus will be described, but it isunderstood that this in no way is to be taken as a limitation on thescope of the invention. The attached drawing is a diagrammatic view ofan apparatus adapted for carrying out the process.

A preheated tar fraction is pumped through line I and valve 2 into thetop of a treating tower 3. A halogen acid or a hydrogen halide isintroduced into the bottom of treating tower 3- through line 4 and'valve 5, for example, a con centrated solution of hydrobromic acid,which has been found to give good results in practice. For every gallonof tar fraction to be treated the amount of hydrogen halide may varyfrom one to five pounds, depending on the characteristics of the tar tobe treated and the extent of treatment desired.

Pressure on the treating tower may vary from substantially atmosphericto several hundred pounds superatmos'pheric pressure. A treatingtemperature above the boiling point of water with a range of from 200 to500 F. is preferred. The

act. iiows upwardly countercurrent to the tar fraction coming from thetop of the treating tower. For the purpose of insuring intimate con tactbetween the tar fractions and the acid, treat- 5 ing tower may containany suitable filling material, such as, for example, coarse silicafragments.

In order to control the temperature in thetower a closed steam coil 8having valves 1 and 8 for regulating quantity of steam in the steam mcoil 8 is placed in the bott m of tower 3.

Treated tar fractions collect in the bottom of treating tower I and fromthence are taken by pump 8 through line Iii and valve II and dischargedinto fractionating column ii. A small 15 quantity of low boilingmaterial is removed from the top of fractionating column I! through lineH and valve l4, subjected to condensation in condenser i8 and thencepassed and collected through line I8 and valve IT in receiver l8. This20 liquid condensate may be withdrawn from the bottom of receiver l8 bymeans of line I! and valve 20. Pressure on the fractionating system iscontrolled by withdrawing fixed gases through valve II in line 22.Subatmospheric pressure is 25 preferably maintained in fractionatingcolumn I condenser l8 and receiver l8 for the purpose of minimizingfurther decomposition and polymerization. From the bottom offractionating column I 2 a heavy pitch is removed from the 3 system bymeans of line 23 and valve 24. The improved inhibitor will constitute anintermediate boiling point fraction and may be removed as a side-cutfrom fractionator i2 through line 28 and valve 28. In order to assist inthe fractionation 35 of the treated tar steam coil 21 is shown in thebottom of fractionator II. A quantity of steam passing through coil 21is regulated by valves 28 and 28.

As the result of the interaction between the 40 tar fraction and thehalogen acid, a mixture of alkyl halides is generated. Under theconditions existing in treating tower I, water and alkyl halide will bein vaporousi'orm and will pass out through the top of treating tower 3through line 45 38 and valve 3i intocondenser 32 wherein the steam iscondensed and thence through line 33 and valve 84 into receiver 38.Separation of the water and alkyl halides (ethyl and methyl bromides forexample) will take place in receiver ll since the boiling point ofwater'is 212 F., and the boiling point of methyl bromide is 40.3 F. andethyl bromide is 100.4 F. The alkyl halides are at most only slightlysoluble in water and, therefore, only a very small quantity will 5 beremoved in solution whenthe water is withdrawn from the bottom of thereceiver through line 38 and valve 81.

For the purpose of regenerating hydrogen halide for use in treatingfurther amounts of tar 5 the alkyl halide is now burned. The alkylhalides, which are as a rule principally methyl bromide, have a low heatof combustion and need to be first heated to high temperatures or elseoxidized with air at high temperatures by means 5 oi a heatedsurrounding medium if they are to be continuously burned. In order,therefore, to aid combustion of the alkyl halide a combustionsupportinggaseous medium is added. The alkyl halide may pass from receiver 35through 70 line 38 and valves 39 and 80 into burner 4|. Air andextraneous fuel gas are supplied to burner II by means of line 42 andvalve 43 and line It and valve 48 respectively. Any hydrocarbon or otherfuel gas will be satisfac- 75 tory in aiding the combustion of the alkylhal- Hydrogen halides are very soluble in water, therefore scrubbingtower 80 is utilized for contacting water with the cooled combustiongases resulting from furnace 48 for the purpose of recovering halogenacids for further use. The water is introduced into the top of thescrubbing tower 80 by means of line 83 and valve 84. Preferably theaqueous acid withdrawn from the bottom of receiver 38 is recirculated tothe top of the tower. A local cyclic circulation to induce greaterabsorption of the acid in water may be set up by returning a portion ofthe liquid acid from the bottom of scrubbing tower 80 and pumping thesame to thetop of the tower by way of line 88 containing valve 88, pump84', line 88' and valve 81. Residual gases after contacting the water inscrubbing tower 88 are released at the top of the tower through line 88and valve 88. and the concentrated acid solution is removed from thebottom of scrubbing tower 50 through line 88 and valves 8| and forced bypump 82 through line 83 containing valve 84 into the bottom of thetreating tower 3 for further treatment of tar.

Fresh acid may be injected directly in line 88 or may be introduced intothe treating tower by means of line 4 and valve 8.

As an alternative method of operation, although not shown in thedrawing, the products 01 combustion may be sent directly to the treatingtower. In that event provision would have to be made to eliminate thenon-reactive constituents, leaving the top of receiver 35 together with.the alkyl halides. This may be accomplished by dissolving the alkylhalides in ethyl alcohol or any other suitable solvent (nitrogen andcarbon dioxide are insoluble in these solvents) recovering the alkylhalides by distillation and subsequently burning the alkyl halides toproduce hydrogen halide together with carbon dioxide, water, andnitrogen, all of which are sent directly to the treating tower. Thusthis invention may be practiced with the use of substantially gaseoushydrogen halide or with varying concentrations of hydrogen halide acid.

Diluents such as the lower aliphatic acids, consisting of acetic,propionic and butyric acids, may be added to the tar for the purpose oflowering the viscosity of such tar and assuring more intimate contactbetween the acid and the tar.

The following is given as an example of the results of operating theprocess of this invention:

The source of raw material was a tar precipitated from the vaporsleaving the wood distillation retorts by means of a Cottrell electricalprecipitator and known as Cottrell tar, and contained about 18% water.This tar was distilled and a fraction obtained boiling between approxi-'mately 140 and 500 F., which was used as a source of material for theproduction of the improved inhibitor.

The tar fraction was introduced into the top of the treating tower whilea concentrated solu tion of hydrobromlc acid was injected into thebottom. An acid solution of hydrogen bromide containing 2.26 pounds ofbromine equivalent-was used per gallon of tar fraction. A reactiontemperature of 280 F. and a pressure of 25 pounds per square inch wasmaintained on the treating tower. As the result of the interactionbetween the tar fraction and the hydrobromic acid methyl bromide wasliberated together with water vapor.

The quantity of methyl bromide recovered per gallon of tar fraction was1.98 pounds, of which 1.66 pounds was bromine. The water vapor andmethyl bromide removed from the top of the treating tower were subjectedto condensation and collected in a receiver at a temperature of 110 F.Separation of practically all of the methyl bromide from the water takesplace under those conditions because methyl bromide is only slightlysoluble in water and even more insoluble in hot water.

The methyl bromide was subjected to combustion in a small furnace withthe simultaneous ad dition of city gas and air. The products ofcombustion were cooled and scrubbed with a portion of the watercondensed from the treating tower. A concentrated solution containingapproximate ly 45% by weight of hydrobromic acid was recovered from theacid-absorbing tower. The bromine recovered in the hydrobromic acidscrubbing solution was 1.45 pounds per gallon of Cottrell tar, thusmaking 64% of the original hydrobromic acid again available for use.Concentrated acid solution recovered by scrubbing of the combustiongases was then mixed with additional fresh hydrobromic acid from anexternal source, such that the quantity of bromine in the hydrobromicacid in the latter mixture was once again 2.26 pounds per gallon ofCottrell tar fraction. The restored acid mixture was then returned forfurther treatment.

The treated tar was withdrawn from the bottom of the treating column andsubjected to fractional distillation under subatmospheric pressure.Approximately 5% of light low boiling material is taken off from the topof the vacuum distillation column. of the treated Cottrell tar isremoved from the bottom of the tower as a heavy pitch.

An intermediate cut constituting 70% of the original material used isremoved as a side-cut. To a crude cracked gasoline was added 0.05% ofthe original tar fraction. The induction period as tested by an oxygenbomb maintained at 212 F. was found to be 410 minutes whereas when0.025% of the treated side-cut was added to a sample of the samegasoline, the induction period was 480 minutes. This side-cut is animproved inhibitor and is more than twice as effective as the originalCottrell tar fraction.

It is to be understood, of course, that the above example is givenmerely for purposes of illustration and is not intended to serve as alimitation on the invention.

We claim as our invention:

1. A process for improving the inhibiting value of tars from thedistillation of solid carbonaceous materials, which comprises reactingsaid tar with hydrogen halides, fractionating the products into volatilealkyl halides and tar fractions of improved inhibiting value, recoveringthe latter, burning the alkyl halides to regenerate hydrogen halides,and returning the regenerated hydrogen halides for further use.

2. A process for improving the inhibiting value of tars from thedistillation of wood, which comprises reacting said tars with hydrogenhalides, fractionating the products into volatile alkyl halides and tarfractions of improved inhibiting value, recovering the latter, burningthe alkyl halides to regenerate hydrogen halides, and returning theregenerated hydrogen halides for I further use.

3. A process for improving'the inhibiting value of tars from thedistillation of lignite, which comprises reacting said tars withhydrogen halides, fractionating the products into volatile alkyl halidesand tar fractions of improved inhibiting value, recovering the latter,burning the alkyl halides to regenerate hydrogen halides, and retumingthe regenerated hydrogen halides for further use.

4. A process for improving the inhibiting value of tars from thedistillation of coal, which comprises reacting said tars with hydrogenhalides, fractionating the products into volatile alkyl halides and tarfractions of improved inhibiting value, recovering the latter, burningthe alkyl halides to regenerate hydrogen halides, and returning theregenerated hydrogen halides for further use.

5. A process for improving the inhibiting value of selected fractions oftars from the distillation of wood, which comprises reacting saidfractions with hydrogen halides, fractionating the products intovolatile alkyl halides and tar fractions of improved inhibiting value,recovering the latter, burning the alkyl halides to regenerate hydrogenhalides, and returning the regenerated hydogen halides for further use.

6. A process for improving the inhibiting value of selected fractions oftars boiling within the approximate range of 200-300 C. from thedistillation of wood which comprises reacting said fractions withhydrogen halides, fractionating the products into volatile alkyl halidesand tar fractions of improved inhibiting value, recovering the latter,burning the alkyl halides to regenerate hydogen halides, and returningthe regenerated hydrogen halides for further use.

7. A process for improving the inhibiting value of selected fractions oftars from the distillation of lignite, which comprises reacting saidfractions with hydrogen halides, fraction'ating the products intovolatile alkyl halides and tar fractions of improved inhibiting value,recovering the latter, burning the alkyl halides to regenerate hydogenhalides, and returning the resaid fractions with hydrogen halides,fractionating the products into volatile alkyl halides and tar fractionsof improved inhibiting value, recovering the latter, burning the alkylhalides to regenerate hydrogen halides, and returning the regeneratedhydrogen halides for further use.

9. A process for improving the inhibiting value of selected fractions oftars from the distillation of coal, which comprises reacting saidfractions with hydrogen halides, i'ractionating the products intovolatile alkyl halides and tar fractions of improved inhibiting value,recovering the latter, burning the alkyl halides to regenerate hydrogenhalides, and returning the regenerated hydrogen halides forfurther use.

10. A process for improving the inhibiting value of selected fractionsof tars from the distillation of coal boiling within the approximaterange of 200300 C. which comprises reacting said fractions with hydrogenhalides, fractionating the products into volatile alkyl halides and tarfractions of improved inhibiting value, recovering the latter, burningthe alkyl halides to regenerate hydrogen halides, and returning theregenerated hydrogen halides for further use.

11. A process for improving the inhibiting value of selected fractionsof tars from the distillation of wood which comprises reacting saidfractions with halogen acids, fractionating the products into volatileall vl halides and tar fractions 01 improved inhibiting value,recovering the latter, burning the alkyl halides to regenerate hydrogenhalidea and returning the regenerated hydrogen halides for further use.

tillation of wood boiling within the approximate range of 200-300 .C.which comprises reacting said fractions with halogen acids,fractionating the products into volatile alkyl halides and tar fractionsof improved inhibiting value, recovering the latter, burning the alkylhalides to regenerate hydrogen halides, and returning the regeneratedhydrogen halides for further use. CHARLES D. LOWRY, J12. CHARLES G.DRYER.

